Telephone-switchboard key



Aug. l2, 1930. R. F. sTEPHENsoN TELEPHONE SWITCHBORD KEY Original Filed-Nov. 12, 1925' AeA/ff Patented Aug. 12, A1930,

ROBERT F. STEPHENSON, OF LOS ANGELES, CALIFORNIA TnLnPHoNE-swnrcrrnoann KEY Reied for abandoned application Serial No. 68,684, filed November 12, 1925. This application led May v 31, 1930. Serial No. 458,763.

This application is a reiile for abandoned application `Ser. No. 68,684, filed Nov. 12, 1925.

My invention relates generally to circuit controllers, and particularly, although not necessarily, to keys for telephone switchboards, by which an operator controls the operators, subscribers and ringing circuits. It is a purpose of my invention to provide a switchboard key which eliminates all bearings, rollers and other wearing parts and the attendant disadvantages, yet possessing maximum durability and ease of operation, and greatly reducing the manufacturing and assembling costs. A

It is also apurpose of my invention to provide a switchboard key which permits various arrangements and combinations of contact arms forcontrolling a plurality of cirl cuits, and a control arm manually movable to various positions for actuating the contact arms, with means operating automatically to releasably secure the control arm in one position for maintaining those contact arms of a particular' circuit closed.

i In the drawings,

Figure 1 is aview showing in horizontal y section one form of switchboard key embodying my invention in applied position to a switchboard panel;

Figure 2 is a perspective view of the switchboard key shown in Figure 1;

Figures 3 and 4 are views showing in side elevation the two eXtreme positions which the key shown in Figure 1 is capable'of occupying;

Figure 5 is adetail perspective view of the magnet shown in Figure 1.

Referring specifically to the drawings, my

. V450 invention in its present embodiment is shown applied to a switchboard panel 15, the latter' being provided with an opening 16 spanned by a plate 17 secured to the panel 15 and providing supporting means for a permanent 4 5 magnet 18, the latter being secured to the plate by screws 19. This magnet is of the form illustrated to advantage in Figure 5, and, as shown, is of U-form, with a boit 2O rotatable in an opening 21 formed in the intermediate portion of the magnet; the headed end 22 of the bolt is disposed eXteriorly of the magnet and is accessible to permit the application of a wrench thereto in effecting rotation of the bolt. The bolt is locked against longitudinal movement by means of a collar 23 keyed to the bolt between the parallel portions Vof the magnet, it being understood that the collar co-operates with the bolt head in locking the bolt against longitudinal movement in either direction. On the threaded portion of thc boit a sleeve 24 is threadedly mounted so as to have sliding contact with the parallel portions of the magnet, but locked against rotation so that when the bolt is rotated the sleeve. will be fed forwardly orV rearwardly, depending upon the direction of rotation of the bolt. This sleeve 241A is formed of magnetic material and is designed by longitudinal adjustment to vary the magnetic flux at the poles of the magnet 18 for a purpose which will be described hereinafter. It will be understood that the sleeve 24 functions as a conductor of high permeability for the magnetic lines of force of the magnet, and that as the sleeve is moved toward or away from the poles of the magnet the flux at the poles will be decreased or increased accordingly.

Secured to the innerV side of the magnet 18 by means of screws 25 is a bracket or frame 26 of substantially L-form, and Ysecured to the inner end of the bracket are a plurality-of bolts 27. the shanks of which are surrounded yby sleeves 28 of insulating material. These bolts 27 serve to secure inside by side relation a plurality of insulating blocks 29 to the bracket 26, and extending between adjacent blocks are a plurality of contact arms and a control arm, with all of the arms provided with yopenings through which the bolts and sleeves 2T and 28 extend. In this manner, the several arms are rigidly supported, and in such manner that one ot their ends projects from the blocks for connection with the conductors, forming the terminals of a telephone circuit, that is, with the exception of the control arm.

In the present embodiment ot my invention, I have shown three pairs ot stationary Contact arms designated, respectively, at 30, 3]. and 32, and two pairs of movable contact arms 33 and 3st-, respectively. All of the contact arms are formed ot single strips of resilient metal capable ot being stamped trom sheets of resilient metal. The control arm, designated at 35, is likewise formed of resilient metal so that it may be flexed to engage and flex the movable contact arms 33 and 84 into engagement with the stationary contact arms 30,31 and 32. As shown in Figure l, the control arms 35 is interposed between the contact arms in such manner that the arms and 33 are disposed at the other side thereof. All of the contact arms are provided with contact projections 36 Yformed of conducting material, and it is to be noted that the movable contact arms 33 and 3a are of greater length than the stationary Contact arms so as to project from one end ot the latter :tor engagement by insulated projections 37 on the control arms 35. The projecting end ot the contact arm 34 is provided with a curved offset portion 34a.

The control arm 35 is ot such length that its tree end projects in front of the poles of the magnet 18, where it is provided with a block ot iron or other suitable metal 38, which is adapted to function as an armature operable by the magnet 18. Secured to the block 38 is a handle 39 which projects trom the forward side ot the switchboard panel apd through a suitable opening in the plate 1r.

he operation oi' the key is as follows: In the normal position ot the several Contact arms they are disposed in parallelism to each other, as shown in Figure l, the contacts 36 ot the arms 3l and 34 engaging each other so as to normally close the subscribers circuit ot which they constitute the terminals. The contact arms 32 and 311 constitute the terminals ot a ringing` circuit, while the arms 30 and constitute the terminals otlr an opera- ;ors circuit. In the normal position o1"A the control arm 85 the armature 38 is beyond the influence ot the magnet l@ so that the control arm normally occupies the position shown in Figi-.ire l. From this normal or intermediate position the control arm is movable to e er oA 'lie two extreme positions illustrated in Figures and l. In the extreme position shown in Figure fl, the armature 2S contacts with the poles ot the magnet 18 and under the influence of the latter is retained in such position. In this extreme position of the control arm the movable Contact arm 33 is flexed to engage the stationary Contact arm 30, thus closing the operators circuit. Then it is desired to disrupt the operators circuit, the handle 39 is pushed to the lett, as when viewed in Figure 3, with sutlicient torce to overcome the attractive torce ot the magnet. Villen moving the control arm to the other extreme position shown in Figure Ll, the contact arm Sil is i'leied to engage the stationary contact arm 32, thereby closing the ringing circuit. It is ot course necessary to manually maintain the control arm in this position to lteep the ringing circuit closed, but when the handle 39 is released the control arm is automatically returned to the normal or intermediate position.

Should the attractive torce ot the magnet J8 vary or weaken, it can be adjusted to retain the armature 38 in contact therewith and with only suliicient torce to overcome the tension of the control arm, by adjustment of the sleeve 34C in the manner previously decribed I claim as my invention:

I. A circuit controller comprising stationary contacts, movable contacts normally urged outot contact with the stationary contacts, a resilient member normally urged to an intermediate position but being capable ot being manually ilexed to one extreme position in which it engages and moves certain of the movable contacts into engagement with certain ot the stationary contacts, and to another eXtreme position to cause tne remaining movable contacts to engage the remaining stationary contacts, and magnetic means for releasably securing the member in one ot said extreme positions.

2. A circuit controller comprising stationary contacts, movable contacts normally urged' out ot contact with the stationary contacts, a member manually operable to one extreme position in which it engages and moves certain of the movable contacts into engagement with cert-ain oi the stationary contacts, and to another extreme position to cause the remaining movable contacts to engage the remaining stationary contacts, a permanent magnet for releasably securing the member in one of the extreme positions,-and means by which the magnetic linx of the magnet at its poles can be varied.

3. A telephone switchboard lrey comprisstationary and movable contacts, the movable contacts being formed. of resilient conducting material and capable of being lieried to engage or dis-engage the stationary contacts. a control arm ot resilient material capable ot being flexed to engage and actuate the movable contacts, an armature on the control arm, and magnetic means enacting with the armature to releasably secure the control arm in a predetermined position when the arm is moved to said position.

4. A telephone switchboard key as embodied in claim 3, wherein said magnetic means comprises a magnet and means adjustable to Vary the magnetic pull exerted thereby on the control arm.

5. A telephone switchboard key as embodied in claim 3, wherein the magnetic switch means comprises a permanent magnet, a permeable element movable between the poles of the magnet to Vary the magnetic flux of the magnet at its poles, and screw means for efecting a positive adjustment ofthe element.

ROBERT F. STEPHENSON. 

